At this pace, the Tories could spend more than £1 million on Facebook ahead of the general elections in May.

On both the invoices provided, the biggest bill was for email collection (£96,617 in September and £71,147 in November). Conservative supporters are encouraged to hand over their email addresses so the party can use them to plead for donations: despite the rise of social media advertising, email is still the main online channel for political campaigns in Britain.

The Conservative Party declined to comment on this particular issue when Business Insider reached out.